Protective bearings guard

ABSTRACT

A bearing guard is adapted for use in connection with a machine such as a chipping/shredding/grinding machine for lawn and garden use. The bearing guard is used in connection with self-aligning bearings which support the ends of a rotatable shaft provided on the machine and which is exposed to a work cavity in which the chipping, shredding or grinding operations take place. The bearing guard protects the bearings from material which is retained on the rotatable shaft during operation of the machine. The bearing guard comprises a shield surface disposed between the work cavity of the machine and the side of the bearing facing the work cavity. The shield surface has an opening through which the rotatable shaft of the machine passes. The opening is in relatively close dimensional tolerance with respect to the outer surface of the shaft, so as to resist contact of material retained on the shaft with the side of bearing during operation of the machine. The shield surface may be disposed on a separate plate structure which is connected to the housing of the machine along with the housing of the bearing, or it may be formed integrally with one of the housing members of the bearing.

BACKGROUND AND SUMMARY

This invention relates to a self-aligning bearing or the like, and moreparticularly to a guard for protecting such a bearing and for prolongingits life.

Self-aligning bearings or the like are used in many applications. Onesuch application is as a support for the ends of a rotatable shaft usedin connection with a chipping/shredding/grinding machine for lawn andgarden use. Such a machine typically has a rotatable shaft disposed inthe lower portion of a housing, to which a hammer assembly is mounted.One bearing assembly is connected to each side of the lower portion ofthe housing, for supporting the ends of the shaft. The shaft and hammerassembly are rotated by means of a motor and drive assembly whichimparts rotation to the shaft. Such rotation of the shaft causesrotation of the hammer assembly which chips, shreds and/or grindsmaterial fed into the lower portion of the housing of the machine.

With the above-described construction, one side of each self-aligningbearing faces toward the interior of the housing of the machine, wherethe chipping, shredding or grinding operation takes place. With thistype of machine, it is common for rope, twine, vines or other such thin,flexible material to wrap around the shaft. An accumulation of suchmaterial on the shaft can cause substantial outward pressure on the sideof the self-aligning bearing facing the interior of the housing. Suchpressure on the side of a self-aligning bearing forces lubricant fromthe bearing, which leads to premature failure of the bearing.

It is an object of the invention to provide a structure which resists orprevents contact of material within a work cavity such as the interiorof the housing of a chipping/shredding/grinding machine, with the innerside of the bearing which supports the shaft adjacent the housing. Inaccordance with the invention, a protective guard for a self-aligningbearing or the like comprises shield means disposed between the workcavity and the side of the bearing facing the work cavity. The shieldmeans has an opening adapted to accommodate passage of the shafttherethrough, and the opening is relatively closely dimensioned to theouter surface of the shaft so as to resist material within the workcavity from contacting the side of the bearing facing the work cavity.In one embodiment, the bearing includes a housing having a projectinglip for retaining the components of the bearing, and the shield meansextends inwardly beyond the projecting lip toward the shaft. The shieldmeans may comprise a cover member adapted to fit over the projecting lipof the housing and having a shielding surface extending inwardlytherefrom toward the shaft. The shield means may alternatively comprisea shielding surface formed integrally with the projecting lip of thebearing housing and extending inwardly therefrom toward the shaft.

A bearing assembly is also provided, generally in accordance with theabove features of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings

FIG. 1 is an isometric view of a chipping/shredding/grinding machinehaving a housing with a rotatable shaft disposed in the lower endthereof;

FIG. 2 is a partial sectional view taken generally along line 2--2 ofFIG. 1;

FIG. 3 is a partial sectional view taken generally along line 3--3 ofFIG. 2; and

FIG. 4 is a partial sectional view similar to a portion of FIG. 2,showing an alternate embodiment of the protective guard of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, a chipping/shredding/grinding machine is showngenerally at 10. Chipping/shredding/grinding machine 10 may beconstructed generally as shown in my copending patent application Ser.No. 07/124,039 filed Nov. 23, 1987, incorporated herein by reference.However, it is to be understood that the subject matter of the presentinvention is not limited to use in connection with a machine as thereindescribed.

Chipping/shredding/grinding machine 10 includes a hopper 12 connected tothe upper end of a housing 14. A chute 16 is connected to the side ofhousing 14. Hopper 12 is adapted to receive leaves or other loose, bulkymaterials to be shredded and ground, while chute 16 is adapted toreceive branches or like objects to be chipped.

With reference to FIG. 2, a hammer assembly 18 is provided in a workcavity 19 in lower end of the interior of housing 14. Hammer assembly 18is mounted to a shaft 20, which extends through the interior of thelower portion of housing 14. Shaft 20 is supported at its ends by meansof a pair of self-aligning bearing assemblies, shown at 22, 24, whichare connected to side walls 25, 26 of work cavity 19 by means of bolts27, 28, respectively, or the like. Self-aligning bearings 22, 24 may bethose such as manufactured by Fafnir Bearing Division of Textron, Inc.under its RA designation, or any other such satisfactory bearing. As isknown, bearings 22, 24 support and accommodate rotation of the ends ofshaft 20.

Shaft 20 is rotated by means of a motor 30 (FIG. 1) which is providedwith a motor sheave around which a belt 32 is trained. As shown in FIG.2, a drive sheave 34 is connected to an end of shaft 20 extending fromhousing 14, and receives belt 32. An idler sheave 36 is disposed betweenthe motor sheave and drive sheave 34, to induce tension in belt 32 as itis driven by motor 30.

With the described construction, shaft 20 is rotatably driven by motor30. Rotation of shaft 20 causes rotation of hammer assembly 18, whichincludes a pair of end plates 38, 40 mounted to shaft 20. A plurality ofpivot bars, such as 42, 44 are connected between end plates 38, 40, andcarry a plurality of staggered hammers, shown at 46. Hammers 46 aremaintained in position by means of a plurality of sleeve-like spacermembers 48, 50, 52 and 54. As described in the above-noted patentapplication Ser. No. 07/124,039, rotation of hammer assembly 18 causeshammers 46 to pivot about pivot bars 42, 44 and to shred and/or grindmaterial contained within the lower end of housing 14.

A knife member, shown at 56, is mounted to end plate 38 and rotatesalong with hammer assembly 18. Knife 56 is provided adjacent the openingof chute 16 into work cavity 19, so as to chip branches or the like asthey are fed therein. A discharge 58 (FIG. 1) is provided in a side ofthe lower portion of housing 14 to discharge material from work cavity19 which has been chipped, shredded or ground by knife 56 and hammerassembly 18.

During operation of machine 10, it is common for slender, flexibleobjects, such as rope, twine or vines, to be fed into the interior ofhousing 14. It is not unusual for such materials to wrap around shaft 20as it rotates. Particularly troublesome are such materials which wraparound shaft 20 between end plates 38, 40 and the sides of housing 14.As these materials accumulate, they exert pressure on the side ofbearing assemblies 22, 24 which faces work cavity 19. Such exertion ofoutward pressure on bearings 22, 24 forces the bearing lubricant fromthe bearings, which leads to premature failure.

With further reference to FIG. 2, self-aligning bearing assembly 24includes a hub 60 to which a rotatable bearing member is centrallymounted. The bearing member is adapted to receive shaft 20. The outerface of hub 60 is in the form of a partial sphere. Bearing assembly 24further includes a housing formed by an inner and an outer flangette.The outer flangette includes a flange 62 having a lip 64 extendingtherefrom, and the inner flangette includes a flange 66 having a lip 68extending therefrom. The inner and outer flangettes are adapted forplacement in a back-to-back relationship, with lips 64, 68 extendingoutwardly therefrom. When so positioned, the inner and outer flangettesdefine a central hub-receiving cavity for retaining hub 60 therein. Lips64, 68 are formed so as to provide a partial spherical inside surfacefor receiving the partial spherical outer face of hub 60, thus providingthe self-aligning feature of bearing assembly 24.

Flanges 62, 66 have a plurality of openings through which bolts, such as28, or other satisfactory fasteners extend to connect bearing assembly24 to side wall 26 of housing 14.

A protective guard for bearing 22 is shown at 70. Guard 70 includes anannular flange portion 72 and a shield portion 74 which is spacedinwardly from flange portion 72. Guard 70 is adapted to be positioned sothat flange 72 is disposed between inner flange 66 of bearing assembly24 and side wall 26 of housing 14. Shield portion 74 extends inwardlythrough the opening formed in side wall 28 and into work cavity 19adjacent hammer assembly 18. A gap is provided between shield portion 74and the inner side of bearing hub 60 to accommodate movement of hub 60during self-alignment.

As shown in FIG. 3, shield portion 74 of guard 70 includes asubstantially central opening 76 for accommodating passage of shaft 20therethrough. Opening 76 is dimensioned so as to be in relatively closeproximity to the outer surfaces of shaft 20. In this manner, entry offibrous material which accumulates on shaft 20 between end plate 40 ofhammer assembly 18 and side wall 26 of work cavity 19 is prevented fromcontacting the side of bearing 24 which faces work cavity 19. Forexample, with shaft 20 having a one inch diameter, opening 76 has adiameter of approximately 1.03 inches.

Guard 70 is preferably made of a material such as aluminum. Whenconstructed of such a material, guard 70 can be positioned such that,even if shaft 20 contacts the edge of opening 76 during self-alignment,there will be no adverse affect either on shaft 20 or guard 70. This isbecause, in most applications, shaft 20 is a hard material such as steelwhich, when it contacts a material such as aluminum in the describedconstruction, simply wears away the aluminum material of guard 70 inorder to accommodate such movement.

Another embodiment of the invention is shown in FIG. 4. In thisembodiment, the inner flangette is again provided with a flange 66 fromwhich a projecting lip 68 extends. A shield surface 78 is integrallyformed with lip 68, extending inwardly therefrom toward shaft 20. Anopening 80 is provided in shield surface 78 to accommodate passage ofshaft 20 therethrough, having substantially the same dimensionaltolerances as described above. A gap is provided between shield surface78 and the inner side of bearing hub 60 to accommodate movement of hub60 during self-alignment.

Various alternatives and modifications are contemplated as being withinthe scope of the following claims particularly pointing out anddistinctly claiming the invention.

I claim:
 1. A bearing assembly, comprising:a rotatable bearing having apassage for accommodating a rotatable shaft therethrough, said shaftextending into structure defining a work cavity where material comesinto contact with and is retained on said shaft; a hub to which saidrotatable bearing is mounted, said hub having a side facing said workcavity; a housing having a hub cavity for receiving said hub thereinsaid a projecting lip on one side of said housing facing said workcavity for retaining said hub within said hub cavity; and shield meansprovided adjacent said hub, said shield means being disposed betweensaid work cavity and the side of said hub facing said work cavity, saidshield means having an opening adapted to accommodate passage of saidshaft therethrough, said opening being located so that said shield meansis in relatively close proximity to the outer surface of said shaft soas to resist contact of material retained on said shaft within said workcavity with the side of said hub facing said work cavity; and whereinsaid shield means extends beyond said projecting lip projecting liptoward said shaft for preventing contact of said material with the sideof said hub facing said work cavity; and wherein said shield meanscomprises a cover member adapted to fit over said projecting lip of saidhousing, said cover member having a shielding surface extending inwardlytoward said shaft and having a substantially central opening foraccommodating passage of said shaft therethrough; and wherein saidhousing includes a pair of flange members adapted for connection to astructural member for mounting said bearing assembly thereto, each saidflange member having an opening thererthrough with said projecting lipadjacent said opening so that, when said pair of flange members arepositioned in a back-to-back relationship with said projecting lipsfacing outwardly, said hub cavity is formed for receiving said hubtherein, and wherein said cover member includes a flange for connectionto said structural member along with said pair of housing flangemembers.
 2. The assembly of claim 1, wherein said cover member issubstantially annular, having a substantially central opening foraccommodating passage of said shaft therethrough and said shieldingsurface extending outwardly therefrom, with said cover member flangebeing disposed adjacent to said shielding surface and extendingoutwardly therefrom.
 3. The assembly of claim 2, wherein said covermember flange is recessed with respect to said shielding surface so asto accommodate said projecting lip of said projecting lip of said flangemember.